Relationship between quinolone use and resistance of Staphylococcus epidermidis in patients with acne vulgaris.

Staphylococcus epidermidis is a bacterium known to inhabit the skin. In treatment of acne vulgaris, the cutaneous milieu is exposed to oral or topical antimicrobials. We previously reported that the antimicrobial resistance of Cutibacterium acnes isolated from acne patients is affected by antimicrobial use. The aim of this study was to investigate the relationship between quinolone use and resistance in skin bacteria, particularly S. epidermidis, from acne patients. A total of 92 and 87 S. epidermidis strains isolated from clinic patients and hospital outpatients with acne vulgaris, respectively, were tested. No significant difference was found between the prevalence of methicillin-resistant S. epidermidis (MRSE) strains from clinic patients (37.0%) and hospital outpatients (39.1%). The MRSE strains (20.6%, 14/68 strains) showed a significantly higher ratio of high-level levofloxacin resistance (minimum inhibitory concentrations were 64 to ≥256 μg/mL) compared with methicillin-susceptible S. epidermidis strains (2.7%, 3/111 strains) (P < 0.01). The rate of levofloxacin resistance in C. acnes strains, which were isolated from the same samples of acne patients, showed a strong positive correlation with that in S. epidermidis strains (r = 0.93, P < 0.01). The high-level levofloxacin-resistant strains were frequently found in patients with history of quinolone use compared with those without (P < 0.01). Our data showed for the first time that antimicrobial administration for acne treatment affects the antimicrobial resistance in not only C. acnes but also S. epidermidis. Thus, caution should be exercised in antimicrobial use for acne treatment to prevent increasing antimicrobial resistance in these species.